Brake mechanism



Dec. 5, 1939. w. A. EATON BRAKE MECHANISM 2 Sheets-Sheet 1 Filed July'7, 1938 an Nu @m n. w l IIQ m E Q m M w u. W MiG- 1 o g0 W v 4/ E kin!l. Mm ydmfl w R @w m Em MN mm @m 9 N m nu R MW l w. A EATON 2,182,,fi47

BRAKE MECHANISM Dec. 5, 1939.

Fiied July '7, 1938 2 Sheets-Sheet 2 Patented Dec. 5, 1939 UNITED STATESPATENT OFFICE Bendix-Westinghouse Automotive Air 'Brake Company,Pittsburgh, Pa., a corporation of Delaware Application July 7, 1938,Serial No. 217,940

17 Claims.

This invention relates to control mechanism for fluid pressure brakesystems and more particularly to a construction whereby the flow offluid in such systems may be efficiently and automatically controlled.

It has heretofore been found desirable in fluid pressure brake systemsfor vehicles of a train having brakes on the different axles to have therear brakes apply first and the other brakes apply progressivelythereafter. Devices such as choked ports have been previously used atsuitable points in the fluid pressure conduits leading to the variousbrake actuators to accomplish this end, but these have had thedisadvantage of delaying the release of the brakes. In order to effect aprogressive brake application on a train of vehicles, it has also beennecessary to progressively graduate the size of the choked ports on thevarious vehicles, making it essential that' the vehicles so equippedoccupy alt-all times the same relative positions in the train.

An object of the present invention is to provide a simple and efficientdevice for effecting a differential rate of fluid flow to differentbrake actuators on a train of vehicles.

Another object is to provide a fluid flow control device adapted toelfect a differential rate of fluid flow to different brake actuatorsduring initial operation thereof and so constituted as to effectequalization of the pressures in said actuators thereafter.

A further object is to provide a fluid flow control device adapted forinstallation on each vehicle of a .vehicle train and so constituted asto efiect a progressive application of the vehicle brakes starting atthe rear end of the train and progressive release of the brakes startingat the front end of thetrain.

A still further object is to provide devices for controlling the flow offluid to a series of brake actuatorswhich will be effective inestablishing progressive operation of the actuators regardless of theircapacity.

Still another object is to provide devices for use with a series ofvehicles for effecting progressive actuation of the brakes thereofregardless of changes in' the relative positions of the vehicles in theseries.

Yet another object is to provide a fluid flow :ontrol device controlledby the flow of fluid to a series of brake actuators to delay theoperation 'of someof the actuators.

These and other objects of the invention will become more readilyapparent from the following description when considered in connectionwith the accompanying drawings. It is to be expressly understood,however, that the drawings are employed for purposes of illustrationonly and are not designed as a definition of the limits of theinvention, reference being had for 5 this purpose to the appendedclaims.

In the drawings, wherein similar reference characters refer to similarparts throughout the several views:

Fig. 1 is a diagrammatic view, partially in section, of a brake systemincorporating a fluid flow control device constructed in accordance withthe principles of the present invention;

Fig. 2 is a diagrammatic view, partially in section, showing theapplication of the control device shown in Fig. 1 to a train of.vehicles.

Fig. 3 is an axial sectional view illustrating a modified form of fluidflow control device which may be employed, and

Fig. 4 is a plan view of a valve member illustrated in section in Fig.3.

Referring more particularly to Fig. 1, a control device 4 constructed inaccordance with the principles of the present invention is disclosedtherein as comprising a casing 5 having an inner wall 6 curved inwardlyat the center of the casing to form a restricted passage 1 and outwardlyat either end to form enlarged passages 8 and 9. Outlet ports l0 and l lare formed in the casing adjacent the enlarged chambers 8 and 9respectively, and the left end of the easing is adapted to threadedlyreceive a nozzle member l2 having a bore l3 therein, said boreterminating in an end portion 14 which may be positioned longitudinallyof the casing at a. point substantially coincident with the reduceddiameter of the restricted passage 1. Suitable bracket portions 15 areprovided on the outside of the casing for'mounting the casing on theframe of the vehicle, not shown. A 40 As further shown in Fig. 1, thefluid flow control device 4 is associated with a fluid pressure brakesystem which may comprise a reservoir IS,

a pair of front brake actuators H, a pair of rear brake actuators l8,and a brake control valve. I9 having an operating lever 20. The brakevalve I9 is preferably of the well known self-lapping type and may beconstructed as set forth in the patent to- Wilfred A. Eaton, No.2,112,484, dated March 29, 1938. The brake actuators l1 and I8 are ofwell known construction having cylinders 2| and 22 enclosing slidablymounted pistons, not shown, and adapted under the influence of a fluidpressure differential to actuate the brake operating levers 23 and 24 bymeans of piston rods 25 and 26 connected thereto by pivot pins 21 and 28respectively. In order that the brake valve may be eifective incontrolling the flow of fluid pressure to and from the actuators i1 andHi to effect application and release of the brakes, a conduit 29 isprovided for conducting fluid pressure from the reservoir [6 to thebrake valve, while a conduit 30 is adapted to conduct fluid pressurefrom the brake valve to the brake actuators l1 and I8 through conduits3| and 32 by virtue of its connection therewith .through bore i3 ofnozzle l2, casing 5 and the outlet ports l0 and II provided in thecasing of the device 4 as heretofore described.

The self-lapping brake valve [9 is provided with the usual inlet andexhaust valves and is operative on movement of lever 20 in one directionto close the exhaust valve and open the intake valve to establishcommunication between conduits 29 and 30, and operative on movementthereof in the other direction to open the exhaust valve to establishcommunication between conduit 30 and an exhaust conduit 33 having aconnection with the exhaust valve of control valve i9. It will thus beseen that, on operation of lever 20, the valve l9 will be effective toconnect conduits 29 and 30 and fluid pressure will be conducted fromreservoir l6 to the rear brake actuators it through conduit 29, valvel9, conduit 30,- bore l3 in nozzle i 2, casing 5 and conduits 32, therapid flow of fluid through nozzle i2 cooperating with the restrictedpassage of'casing 5 to create a partial vacuum in the enlarged chamber 8of the casing which will evacuate a portion of fluid from the frontbrake actuators I! through p'orts l0 and conduits 3|. If the lever 20 isnow held in a given position, it will be apparent that the valve l9, byvirtue of its self-lapping action, will act to maintain a correspondingpressure in conduit 30, and the pressures in conduit'3ll, nozzle l2,casing 5, conduits32 and actuators l8 will tend to become equalized,resulting in a reduction in the rate of fluid flow through the nozzle'2. Since the pumping or evacuating action of the fluid flowcontroldevice 4 is dependent on the velocity of fluid flow through thenozzle l2, it will be evident that, as the rate of flow diminishes, apoint will be reached when the pressure tirely different from thathereinbefore explained.

Movement of the lever 20 as above described will condition the controlvalve l9 to establish a connection between conduit 30 and the exhaustconduit 33, whereupon fluid pressure will be released to atmosphere fromthe front and rear brake actuators l1 and I8 through conduits 3| and 32and ports l0 and II respectively, and thence through casing 5, bore I3of nozzle l2, conduit 30, control valve i9 and exhaust conduit 33. Itwill be apparent, therefore, that the flow of fluid in casing 5 will befrom both ends toward the center with the result that fluid is releasedfrom the front and rear brake chambers at approximately the same rate ifthe conduits 3| and 32 are of substantially equal length. I There hasthus been rovided in the il strated and hereinbefore described structurea novel and eificient device having no moving or wearing parts, andwhich is highly effective in automatically insuring progressiveapplication of different brakes on a vehicle without in any waylessening the degree of application of one brake in relation toanother-on completion of the application.

While the invention has been described above as being incorporated inthe brake system of a single vehicle, it will be evident that it may beapplied with equal effectiveness to the brake systems of a series ofvehicles, as on a tractortrailer train, it being well known that, withthe ordinary fluid pressure brake systems now in use, there is atendency for the brakes to apply on the leading vehicle first andsequentially on the following vehicles. This sequence of brakeapplication often results in skidding of the vehicles, and whenoperating on slippery pavements has often been the cause of serious andcostly accidents.

Referring more'particularly to Fig. 2 of the drawings, whereinapplicant's novel fluid flow control system is illustrated as applied toa train of vehicles which may include a tractor and two trailers,indicated diagrammatically, it is to be noted that each vehicle isequipped with a. fluid flow control device 4. The self-lapping brakevalve I 9 is adapted to supply fluid pressure to the device 4 on thetractor through conduit 30 and thence to the similar devices 4 on thefollowing vehicles through conduits 34, 35, 36 and 31, and provision ismade for supplying air to an additional vehicle through conduits 38 and39 and coupling device 40, a valve 4| inconduit 39 being normally closedto prevent the escape of fluid through the coupling device 4|]. Thevehicles of the train are equipped with brake actuators I1, 45 and 46respectively, and the fluid flow control devices 4 of the correspondingvehicles are connected thereto by means of ports l0 and conduits 42, 43and 44.- It will be apparent from the foregoing description that theseries of conduits 30, 34, 35, 36, 31 and 39 form a conduit common toall the vehicles of the train. while the control devices 4 on thedifferent vehicles are adapted to establish a connection between thecommon conduit and the brake actuators I1, 45 and 46 through thecorresponding conduits 42, 43 and 44.

If the brake valve is now'operated to effect a brake application, fluidpressure will flow from the reservoir iii to the series of conduits 30,34,-

35, 36, 31 and '39 forming the common conduit as heretofore described,through conduit 29 and valve l9, the flow of fluid through the devices 4cooperating therewith to successively evacuate the actuators i1, 45 and4B in the manner already described. Due to the fact that the volume ofthe portions 38 and 39 of the common conduit at the rear of the device 4on the second trailer is relatively small, however, the pressure in thecasing 5 of the device will build up very rapidly,

conduits 44. As the pressure builds up in actu-' ators 46, the velocityof fluid flow through nozzle l2 of device 4 on the first trailer willdecrease to a value such that the evacuating effect of the fluid flowingthrough the device on the first trailer will cease, and fluid pressurewill flow from the common conduit through device 4, and conduits 43 tothe brake actuators 45 on the first trailer, it being obvious that thisaction will take place after the initiation of a brake application onthe second trailer. In like manner, fluid pressure will be conductedthereafter to brake actuators I! on the tractor through device 4 andcon- .duits 42, and, if thebrake valve lever 20 is held in a position toeffect a predetermined degree of brake application, the pressures in thevarious parts of the system will eventually equalize and the brake valveI9, by virtue of its self-lapping property, will act to maintain thepredetermined pressure in the brake system. On operation of the brakevalve to release the brakes, the devices 4 will not materially effectthe flow of fluid from the actuators through the brake valve and thenceto atmosphere through exhaust conduit 33, and the actuators on thetractor, being nearest the brake valve, will start to exhaust first, theactuators of the first and second trailers starting to exhaustthereafter in the sequence named, as would be the case in the ordinaryfluid 'brake system having the common conduit connected to actuatorsupply conduits 42, 43 and 44 through ordinary pipe connections insteadof through the fluid flow control devices 4. This latter action is wellknown and also desirable in the operation of the common single pipefluid pressure brake system, and it will be apparent from the foregoingdescription that the inclusion of the fluid flow control devices in asystem of this type not only retains the advantages inherent therein,but also overcomes in a simple and eflicient manner the tendency of suchsystems to initiate a brake application at the forward end of thetrain,-the result being .that the tendency of the rear vehicles to runin on the forward vehicles is eliminated under all condit ons of brakeapplication and release.

A modified form of fluid flow control device 41 is illustratedin Fig. 3.As illustrated, the valve comprises a casing 41a provided with an inletport 48 and outlet ports 49, the right end of the casing being adaptedto threadedly receive a closure member 50 having a member 5| extendinginto the casing and forming a chamber 5| a therein. The member 5| isformed with a bore 53, substantially in alignment with the inlet port48, and provides an additional outlet port from the casing 41a. A valveseat 52 is formed on the left end of member 5|. In'order that the flowof fluid through the casing 4111 may be controlled in accordance withthe principles of the present invention, a valve member 54 having guideflngers 55 formed thereon and having also a relatively restricted port55a through the center thereof is positioned within the casing 410 andis normally urged against stops 56 as by means of a spring 51 interposedbetween the closure member 50 and the valve member. The valve is thusnormally maintained in spaced relationship with respect to the valveseat 52 formed on the member 5|, and, in view of the arrangement of thevalve guide fingers 55, illustrated in detail in Fig. 4 of the drawings,it will be noted that the inlet port 48, the outlet ports 49 and thebore 53 are in substantially unrestricted communication flow of fluidthrough port 43 exceeds a predetermined rate, the valve being thereafterheld against the seat 52 by virtue of the pressure differential betweenchamber 51a and bore 53 set up by the action of the relatively smallport 55a of the valve.

The valve device described above is more particularly adapted to effectprogressive application of two sets of brakes, and, if it is desired tosubstitute it for the device 4 in the system illustrated in Fig. 1 thismay be accomplished by connecting conduits 3| to bore 53 of the valve bythe use of ordinary tubing fittings, not shown, and by connectingconduits 32 to ports 49 in like manner, the brake valve is beingconnected to the chamber 5Ia of the valve 41 by means of conduit 30 andport 48. On operation of the brake valve to .supply fluid pressure toconduit 30, it will be apparent that the impact of the fluid against theleft face of valve member 54 will move the valve against the seat 52,thus providing a restricted connection between the brake chambers i1 andthe valve chamber 5: through conduits 3|, bore 53 and port 55a, andrelatively unrestricted communication between brake chambers .l8 and thevalve chamber 5Ia through conduits 32 and ports 49. Thu the pressure inthe rear brake chambers will build up at a faster rate than that in thefront brake chambers, resulting in progressiveapplication of the rearand front brakes. As the pressures build up in chamber 5la. and bore 53,they willtend to equalize through the valve port 55a, and the forceexerted on the valve toward the right by the pressure differentialbetween chamber 5| a and bore 53 will eventually become less than theforce exerted on the valve toward the left by spring 51, at which timethe valve will be moved to open position and conditioned to permit arelatively unrestricted exhaust of fluid from all the brake chambers onsubsequent brake releasing operation of the brake valve.

While two embodiments of the invention have been disclosed herein andhave been described with considerable particularity, it is to beunderstood that the invention is not limited thereto, and variouschanges may be resorted to without departing from the spirit of theinvention. Reference will, therefore, be had to the appended claims fora definition of the limits of the inven tion.

What is claimed is:

l. A fluid pressure brake system including apair of brake actuators,conduits for supplying fluid pressure to each of said actuators, meansfor supplying fluid pressure to said conduits, and means for connect ngsaid first named means with said conduits and responsive to the flow offluid therethrough to one of said actuators for temporarily evacuatingsaid other actuator and delaying the flow of fluid thereto.

2. A fluid pressure brake system including a pair of brake actuators,conduits for supplying fluid pressure to each of said actuators, meansfor supplying fluid pressure. to said conduits, and means for connectingsaid conduits and said first named means and responsive to the rate offluid flow therethrough to one of said actuators for controlling therate of fluid flow to said other actuator.

3. A fluid pressure brake system including a pair of brake actuators,conduits for supplying fluid pressure to each of said actuators, meansfor supplying fluid pressure to said conduits, and means for connectingsaid conduits and first named means and responsive to the rate of fluidlimiting the fluid flow to said other actuator to a rate less than therate of flow to said first named actuator.

4. A fluid pressure brake system vfor vehicles including front brakeactuators, rear brake actuators, conduits for supplying fluid pressureto said front brake actuators, conduits for supplying fluid pressure tosaid rear brake actuators, means for supplying fluid pressure to saidconduits for eflecting a brake application, and means including a jetand a Venturi tube for connecting said first named means and conduits,the flow of fluid pressure through said jet to said rear brake actuatorscooperating with said Venturi tube to evacuate said front brakeactuators.

5. A fluid pressure brake system foraplurality of vehicles including abrake actuator on eachvehicle, a conduit carried by each vehicle forsupplying fluid pressure to said actuator, a conduit common to all ofthe vehicles for supplying fluid pressure to said vehicle-carriedconduits, means carried by the leading vehicle for supplying fluidpressure to said common conduit for effecting a brake application, andfluid flow control means carried by each vehicle for connecting saidvehicle-carried conduits with said common conduit, said means beingrendered effective by the flow of fluid pressure therethrough from thesupply means on the leading vehicle to the brake actuator on the rearvehicle through said common conduit for progressively supplying fluidpressure to the brake actuators on the forward vehicles subsequent tothe supplying of fluid pressure to the brake actuator on the rearvehicle.

6. A fluid pressure brake system for a train of vehicles including abrake actuator on each vehicle, a conduit carried by each vehicle forsupplying fluid pressure to said actuator, a conduit common to all thevehicles for supplying fluid pressure to said vehicle-carried conduits,means carried by the leading vehicle for supplying fluid pressure tosaid common conduit for efiecting a brake application, and meansincluding a jet and a Venturi tube carried by each vehicle forconnecting said vehicle-carried conduits and said common conduit, theflow of fluid pressure from the leading vehicle supply means to theactuator on the rear vehicle through said common conduit and jetscooperating with said Venturi tube for thereafter progressivelysupplying fluid pressure to the actuators on the forward vehicles.

7. In a fluid pressure brake system, a source of fluid pressure, a pairof brake actuators, means including a conduit connected to said sourceand conduits connected to said brake actuators for conducting fluidpressure from the source to said actuators for effecting a brakeapplication, and common connecting means for said conduits including avalve operable by the flow of fluid pressure therethrough to one of saidactuators for limiting the rate of fluid flow therethrough to said otheractuator.

8. .In a fluid pressure brake system, a source of fluid pressure, a pairof brake actuators, conduits connected to said actuators, a conduitconnected to said source, valvular means associated with said last namedconduit for controlling the flow of fluid pressure to said actuators,and common connecting means for said valvular means and first namedconduits including a resiliently biased valve so constituted as toprovide unrestricted communication between said valvular means andactuators during the flow of fluid pressure therethrough at a lowvelocity and operable by the flow of fluid pressure therethrough at a.higher velocity for restricting the rate of flow of fluid pressure toone of said actuators.

9. The combination with a fluid pressure brake system including a sourceof fluid pressure, a pair of brake actuators and means including a valvefor controlling the flow of fluid pressure to said actuators, of meansfor connecting said valve and actuators including a device operable bythe flow of fluid pressure therethrough to one of said actuators forlimiting the rate of flow of fluid pressure to said other actuator.

10. In a fluid pressure brake system, means for controlling the flow offluid from a source of fluid pressure to a pair of fluid motorscomprising a casing having an inlet port and outlet ports, and meansresponsive to the rate of flow of fluid through said inlet port forpartially closing one of said outlet ports.

11. In a fluid presure brake system, means for controlling the flow offluid from a source of fluid pressure to a pair of fluid motorsincluding a casing having an inlet port and outlet ports, and normallyopen valve means associated with one of said outlet ports and operableby the flow of fluid through said inlet port at a rate exceeding apredetermined velocity for partially closing said one outlet port.

12. In a fluid pressure brake system, means for controlling the flow offluid from a source of fluid pressure to a pair of fluid motorsincluding a casing having outlet ports, a valve member movable forpartially closing one of said ports, resilient means for normallymaintaining said valve member in open position, and an inlet port fordirecting a jet of fluid from said source against said valve for movingit to port closing position.

13. In a fluid pressure brake system, means forcontrolling the flow offluid from a source of fluid pressure to a pair of fluid motorsincluding a casing having a Venturi tube formed therein and outlet portsleading therefrom, and an inlet port for directing a jet of fluid fromsaid source through said Venturi tube for efiecting a differential inthe rate of fluid flow through said outlet ports to said motors.

14. A fluid pressure brake system including a pair of brake actuators,conduits for supplying fluid pressure to each of said actuators, meansincluding a valve operable for controlling the flow of fluid pressure toand from said actuators, and means connecting said valve and conduitsfor effecting a differential rate of flow of fluid from the valve tosaid actuators and a substantially equal rate of flow of fluid from saidactu-.

ators to atmosphere during corresponding controlling operations of saidvalve.

15. A fluid pressure brake system for a plurality of vehicles includinga brake actuator on each vehicle, a conduit carried by each vehicle forconducting fluid presure to and from said actuator, a conduit common toall of said vehicles for conducting fluid pressure to and from saidvehicle-carried conduits, means carried by the leading vehicle forcontrolling the flow of fluid pressure to and from said common conduit,and means carried by each vehicle for connecting said common conduitwith said vehicle-carried conduits, said last named means beingresponsive to the flow of fluid pressure in the common condui toward therearmost vehicle for effecting progressive application of pressure tothe brake actuators starting at the rear vehicle, and being efiective ona reverse flow of fluid pressure through said 76 common conduit forinsuring the release of pressure from said actuators in reverse order.

16. In a brake system having a pair of fluid motors for actuating thebrakes, conduits for conducting fluid to and from the motors, means forcontrolling the application of a fluid pressure differential to saidmotors, and means for connecting said conduits and controlling means andresponsive to the rate of flow of fluid there- 10 through to one of saidmotors from said controlling means for effecting a different rate offluid flow to said other motor.

17. In a fluid pressure braking system having a plurality of brakeactuators, means for conducting fluid pressure to said actuators, andmeans associated with said conducting means and responsive to the flowof fluid therethrough to some of said actuators for delaying the flow offluid pressure to other of said actuators.

WILFRED A. EATON.

